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Editorial Team
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Asked: 2026-05-17T17:58:55+00:00

ArrayList<HashMap<String, String>> arrayListRowsFirst = new ArrayList<HashMap<String, String>>(); Today when i was going through a

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ArrayList<HashMap<String, String>> 
arrayListRowsFirst = new ArrayList<HashMap<String, String>>();

Today when i was going through a code, this piece of code struck me for a while. Here are some of my questions over this declaration.

  1. What could be the requirement if one has to append an HashMap into an ArrayList.
  2. What will happen during sorting of arraylist, how it will go, will it take long time.
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1 Answer

  1. Editorial Team

    First off, “generic chaining” in my opinion is a poor practice. I would encourage wrapping the HashMap in a class that encapsulates the data inside, allowing the logic for manipulation to be inside the class, not just strewn about everywhere.

    To answer #1, I could think of a number of scenarios. You might have languages for instance, mapping certain constants to other translations. The fact that it says rows first in the identifier makes me think perhaps it’s some kind of matrix of data, and that the first String parameter will exist in all the entries of the list (a poor practice indeed.)
    Edit: I misunderstood your question, it appears. You would add it like any other entry. See the others’ answers for example code. 🙂

    To answer #2, you won’t be able to sort the ArrayList unless you are able to provide a comparator, at which point it’s up to you how it’s sorted (could be size, could be the value of a particular key, could be Math.random(), it’s up to whoever writes the comparator).

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